// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2015 Benoit Jacob <benoitjacob@google.com>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <fstream>
#include <iostream>
#include <memory>
#include <vector>

bool eigen_use_specific_block_size;
int eigen_block_size_k, eigen_block_size_m, eigen_block_size_n;
#define EIGEN_TEST_SPECIFIC_BLOCKING_SIZES eigen_use_specific_block_size
#define EIGEN_TEST_SPECIFIC_BLOCKING_SIZE_K eigen_block_size_k
#define EIGEN_TEST_SPECIFIC_BLOCKING_SIZE_M eigen_block_size_m
#define EIGEN_TEST_SPECIFIC_BLOCKING_SIZE_N eigen_block_size_n
#include <Eigen/Core>

#include <bench/BenchTimer.h>

using namespace Eigen;
using namespace std;

static BenchTimer timer;

// how many times we repeat each measurement.
// measurements are randomly shuffled - we're not doing
// all N identical measurements in a row.
const int measurement_repetitions = 3;

// Timings below this value are too short to be accurate,
// we'll repeat measurements with more iterations until
// we get a timing above that threshold.
const float min_accurate_time = 1e-2f;

// See --min-working-set-size command line parameter.
size_t min_working_set_size = 0;

float max_clock_speed = 0.0f;

// range of sizes that we will benchmark (in all 3 K,M,N dimensions)
const size_t maxsize = 2048;
const size_t minsize = 16;

typedef MatrixXf MatrixType;
typedef MatrixType::Scalar Scalar;
typedef internal::packet_traits<Scalar>::type Packet;

static_assert((maxsize & (maxsize - 1)) == 0, "maxsize must be a power of two");
static_assert((minsize & (minsize - 1)) == 0, "minsize must be a power of two");
static_assert(maxsize > minsize, "maxsize must be larger than minsize");
static_assert(maxsize < (minsize << 16), "maxsize must be less than (minsize<<16)");

// just a helper to store a triple of K,M,N sizes for matrix product
struct size_triple_t
{
	size_t k, m, n;
	size_triple_t()
		: k(0)
		, m(0)
		, n(0)
	{
	}
	size_triple_t(size_t _k, size_t _m, size_t _n)
		: k(_k)
		, m(_m)
		, n(_n)
	{
	}
	size_triple_t(const size_triple_t& o)
		: k(o.k)
		, m(o.m)
		, n(o.n)
	{
	}
	size_triple_t(uint16_t compact)
	{
		k = 1 << ((compact & 0xf00) >> 8);
		m = 1 << ((compact & 0x0f0) >> 4);
		n = 1 << ((compact & 0x00f) >> 0);
	}
};

uint8_t
log2_pot(size_t x)
{
	size_t l = 0;
	while (x >>= 1)
		l++;
	return l;
}

// Convert between size tripes and a compact form fitting in 12 bits
// where each size, which must be a POT, is encoded as its log2, on 4 bits
// so the largest representable size is 2^15 == 32k  ... big enough.
uint16_t
compact_size_triple(size_t k, size_t m, size_t n)
{
	return (log2_pot(k) << 8) | (log2_pot(m) << 4) | log2_pot(n);
}

uint16_t
compact_size_triple(const size_triple_t& t)
{
	return compact_size_triple(t.k, t.m, t.n);
}

// A single benchmark. Initially only contains benchmark params.
// Then call run(), which stores the result in the gflops field.
struct benchmark_t
{
	uint16_t compact_product_size;
	uint16_t compact_block_size;
	bool use_default_block_size;
	float gflops;
	benchmark_t()
		: compact_product_size(0)
		, compact_block_size(0)
		, use_default_block_size(false)
		, gflops(0)
	{
	}
	benchmark_t(size_t pk, size_t pm, size_t pn, size_t bk, size_t bm, size_t bn)
		: compact_product_size(compact_size_triple(pk, pm, pn))
		, compact_block_size(compact_size_triple(bk, bm, bn))
		, use_default_block_size(false)
		, gflops(0)
	{
	}
	benchmark_t(size_t pk, size_t pm, size_t pn)
		: compact_product_size(compact_size_triple(pk, pm, pn))
		, compact_block_size(0)
		, use_default_block_size(true)
		, gflops(0)
	{
	}

	void run();
};

ostream&
operator<<(ostream& s, const benchmark_t& b)
{
	s << hex << b.compact_product_size << dec;
	if (b.use_default_block_size) {
		size_triple_t t(b.compact_product_size);
		Index k = t.k, m = t.m, n = t.n;
		internal::computeProductBlockingSizes<Scalar, Scalar>(k, m, n);
		s << " default(" << k << ", " << m << ", " << n << ")";
	} else {
		s << " " << hex << b.compact_block_size << dec;
	}
	s << " " << b.gflops;
	return s;
}

// We sort first by increasing benchmark parameters,
// then by decreasing performance.
bool
operator<(const benchmark_t& b1, const benchmark_t& b2)
{
	return b1.compact_product_size < b2.compact_product_size ||
		   (b1.compact_product_size == b2.compact_product_size &&
			((b1.compact_block_size < b2.compact_block_size ||
			  (b1.compact_block_size == b2.compact_block_size && b1.gflops > b2.gflops))));
}

void
benchmark_t::run()
{
	size_triple_t productsizes(compact_product_size);

	if (use_default_block_size) {
		eigen_use_specific_block_size = false;
	} else {
		// feed eigen with our custom blocking params
		eigen_use_specific_block_size = true;
		size_triple_t blocksizes(compact_block_size);
		eigen_block_size_k = blocksizes.k;
		eigen_block_size_m = blocksizes.m;
		eigen_block_size_n = blocksizes.n;
	}

	// set up the matrix pool

	const size_t combined_three_matrices_sizes =
		sizeof(Scalar) *
		(productsizes.k * productsizes.m + productsizes.k * productsizes.n + productsizes.m * productsizes.n);

	// 64 M is large enough that nobody has a cache bigger than that,
	// while still being small enough that everybody has this much RAM,
	// so conveniently we don't need to special-case platforms here.
	const size_t unlikely_large_cache_size = 64 << 20;

	const size_t working_set_size = min_working_set_size ? min_working_set_size : unlikely_large_cache_size;

	const size_t matrix_pool_size = 1 + working_set_size / combined_three_matrices_sizes;

	MatrixType* lhs = new MatrixType[matrix_pool_size];
	MatrixType* rhs = new MatrixType[matrix_pool_size];
	MatrixType* dst = new MatrixType[matrix_pool_size];

	for (size_t i = 0; i < matrix_pool_size; i++) {
		lhs[i] = MatrixType::Zero(productsizes.m, productsizes.k);
		rhs[i] = MatrixType::Zero(productsizes.k, productsizes.n);
		dst[i] = MatrixType::Zero(productsizes.m, productsizes.n);
	}

	// main benchmark loop

	int iters_at_a_time = 1;
	float time_per_iter = 0.0f;
	size_t matrix_index = 0;
	while (true) {

		double starttime = timer.getCpuTime();
		for (int i = 0; i < iters_at_a_time; i++) {
			dst[matrix_index].noalias() = lhs[matrix_index] * rhs[matrix_index];
			matrix_index++;
			if (matrix_index == matrix_pool_size) {
				matrix_index = 0;
			}
		}
		double endtime = timer.getCpuTime();

		const float timing = float(endtime - starttime);

		if (timing >= min_accurate_time) {
			time_per_iter = timing / iters_at_a_time;
			break;
		}

		iters_at_a_time *= 2;
	}

	delete[] lhs;
	delete[] rhs;
	delete[] dst;

	gflops = 2e-9 * productsizes.k * productsizes.m * productsizes.n / time_per_iter;
}

void
print_cpuinfo()
{
#ifdef __linux__
	cout << "contents of /proc/cpuinfo:" << endl;
	string line;
	ifstream cpuinfo("/proc/cpuinfo");
	if (cpuinfo.is_open()) {
		while (getline(cpuinfo, line)) {
			cout << line << endl;
		}
		cpuinfo.close();
	}
	cout << endl;
#elif defined __APPLE__
	cout << "output of sysctl hw:" << endl;
	system("sysctl hw");
	cout << endl;
#endif
}

template<typename T>
string
type_name()
{
	return "unknown";
}

template<>
string
type_name<float>()
{
	return "float";
}

template<>
string
type_name<double>()
{
	return "double";
}

struct action_t
{
	virtual const char* invokation_name() const
	{
		abort();
		return nullptr;
	}
	virtual void run() const { abort(); }
	virtual ~action_t() {}
};

void
show_usage_and_exit(int /*argc*/, char* argv[], const vector<unique_ptr<action_t>>& available_actions)
{
	cerr << "usage: " << argv[0] << " <action> [options...]" << endl << endl;
	cerr << "available actions:" << endl << endl;
	for (auto it = available_actions.begin(); it != available_actions.end(); ++it) {
		cerr << "  " << (*it)->invokation_name() << endl;
	}
	cerr << endl;
	cerr << "options:" << endl << endl;
	cerr << "  --min-working-set-size=N:" << endl;
	cerr << "       Set the minimum working set size to N bytes." << endl;
	cerr << "       This is rounded up as needed to a multiple of matrix size." << endl;
	cerr << "       A larger working set lowers the chance of a warm cache." << endl;
	cerr << "       The default value 0 means use a large enough working" << endl;
	cerr << "       set to likely outsize caches." << endl;
	cerr << "       A value of 1 (that is, 1 byte) would mean don't do anything to" << endl;
	cerr << "       avoid warm caches." << endl;
	exit(1);
}

float
measure_clock_speed()
{
	cerr << "Measuring clock speed...                              \r" << flush;

	vector<float> all_gflops;
	for (int i = 0; i < 8; i++) {
		benchmark_t b(1024, 1024, 1024);
		b.run();
		all_gflops.push_back(b.gflops);
	}

	sort(all_gflops.begin(), all_gflops.end());
	float stable_estimate = all_gflops[2] + all_gflops[3] + all_gflops[4] + all_gflops[5];

	// multiply by an arbitrary constant to discourage trying doing anything with the
	// returned values besides just comparing them with each other.
	float result = stable_estimate * 123.456f;

	return result;
}

struct human_duration_t
{
	int seconds;
	human_duration_t(int s)
		: seconds(s)
	{
	}
};

ostream&
operator<<(ostream& s, const human_duration_t& d)
{
	int remainder = d.seconds;
	if (remainder > 3600) {
		int hours = remainder / 3600;
		s << hours << " h ";
		remainder -= hours * 3600;
	}
	if (remainder > 60) {
		int minutes = remainder / 60;
		s << minutes << " min ";
		remainder -= minutes * 60;
	}
	if (d.seconds < 600) {
		s << remainder << " s";
	}
	return s;
}

const char session_filename[] = "/data/local/tmp/benchmark-blocking-sizes-session.data";

void
serialize_benchmarks(const char* filename, const vector<benchmark_t>& benchmarks, size_t first_benchmark_to_run)
{
	FILE* file = fopen(filename, "w");
	if (!file) {
		cerr << "Could not open file " << filename << " for writing." << endl;
		cerr << "Do you have write permissions on the current working directory?" << endl;
		exit(1);
	}
	size_t benchmarks_vector_size = benchmarks.size();
	fwrite(&max_clock_speed, sizeof(max_clock_speed), 1, file);
	fwrite(&benchmarks_vector_size, sizeof(benchmarks_vector_size), 1, file);
	fwrite(&first_benchmark_to_run, sizeof(first_benchmark_to_run), 1, file);
	fwrite(benchmarks.data(), sizeof(benchmark_t), benchmarks.size(), file);
	fclose(file);
}

bool
deserialize_benchmarks(const char* filename, vector<benchmark_t>& benchmarks, size_t& first_benchmark_to_run)
{
	FILE* file = fopen(filename, "r");
	if (!file) {
		return false;
	}
	if (1 != fread(&max_clock_speed, sizeof(max_clock_speed), 1, file)) {
		return false;
	}
	size_t benchmarks_vector_size = 0;
	if (1 != fread(&benchmarks_vector_size, sizeof(benchmarks_vector_size), 1, file)) {
		return false;
	}
	if (1 != fread(&first_benchmark_to_run, sizeof(first_benchmark_to_run), 1, file)) {
		return false;
	}
	benchmarks.resize(benchmarks_vector_size);
	if (benchmarks.size() != fread(benchmarks.data(), sizeof(benchmark_t), benchmarks.size(), file)) {
		return false;
	}
	unlink(filename);
	return true;
}

void
try_run_some_benchmarks(vector<benchmark_t>& benchmarks, double time_start, size_t& first_benchmark_to_run)
{
	if (first_benchmark_to_run == benchmarks.size()) {
		return;
	}

	double time_last_progress_update = 0;
	double time_last_clock_speed_measurement = 0;
	double time_now = 0;

	size_t benchmark_index = first_benchmark_to_run;

	while (true) {
		float ratio_done = float(benchmark_index) / benchmarks.size();
		time_now = timer.getRealTime();

		// We check clock speed every minute and at the end.
		if (benchmark_index == benchmarks.size() || time_now > time_last_clock_speed_measurement + 60.0f) {
			time_last_clock_speed_measurement = time_now;

			// Ensure that clock speed is as expected
			float current_clock_speed = measure_clock_speed();

			// The tolerance needs to be smaller than the relative difference between
			// clock speeds that a device could operate under.
			// It seems unlikely that a device would be throttling clock speeds by
			// amounts smaller than 2%.
			// With a value of 1%, I was getting within noise on a Sandy Bridge.
			const float clock_speed_tolerance = 0.02f;

			if (current_clock_speed > (1 + clock_speed_tolerance) * max_clock_speed) {
				// Clock speed is now higher than we previously measured.
				// Either our initial measurement was inaccurate, which won't happen
				// too many times as we are keeping the best clock speed value and
				// and allowing some tolerance; or something really weird happened,
				// which invalidates all benchmark results collected so far.
				// Either way, we better restart all over again now.
				if (benchmark_index) {
					cerr << "Restarting at " << 100.0f * ratio_done << " % because clock speed increased.          "
						 << endl;
				}
				max_clock_speed = current_clock_speed;
				first_benchmark_to_run = 0;
				return;
			}

			bool rerun_last_tests = false;

			if (current_clock_speed < (1 - clock_speed_tolerance) * max_clock_speed) {
				cerr << "Measurements completed so far: " << 100.0f * ratio_done << " %                             "
					 << endl;
				cerr << "Clock speed seems to be only " << current_clock_speed / max_clock_speed
					 << " times what it used to be." << endl;

				unsigned int seconds_to_sleep_if_lower_clock_speed = 1;

				while (current_clock_speed < (1 - clock_speed_tolerance) * max_clock_speed) {
					if (seconds_to_sleep_if_lower_clock_speed > 32) {
						cerr << "Sleeping longer probably won't make a difference." << endl;
						cerr << "Serializing benchmarks to " << session_filename << endl;
						serialize_benchmarks(session_filename, benchmarks, first_benchmark_to_run);
						cerr << "Now restart this benchmark, and it should pick up where we left." << endl;
						exit(2);
					}
					rerun_last_tests = true;
					cerr << "Sleeping " << seconds_to_sleep_if_lower_clock_speed
						 << " s...                                   \r" << endl;
					sleep(seconds_to_sleep_if_lower_clock_speed);
					current_clock_speed = measure_clock_speed();
					seconds_to_sleep_if_lower_clock_speed *= 2;
				}
			}

			if (rerun_last_tests) {
				cerr << "Redoing the last "
					 << 100.0f * float(benchmark_index - first_benchmark_to_run) / benchmarks.size()
					 << " % because clock speed had been low.   " << endl;
				return;
			}

			// nothing wrong with the clock speed so far, so there won't be a need to rerun
			// benchmarks run so far in case we later encounter a lower clock speed.
			first_benchmark_to_run = benchmark_index;
		}

		if (benchmark_index == benchmarks.size()) {
			// We're done!
			first_benchmark_to_run = benchmarks.size();
			// Erase progress info
			cerr << "                                                            " << endl;
			return;
		}

		// Display progress info on stderr
		if (time_now > time_last_progress_update + 1.0f) {
			time_last_progress_update = time_now;
			cerr << "Measurements... " << 100.0f * ratio_done << " %, ETA "
				 << human_duration_t(float(time_now - time_start) * (1.0f - ratio_done) / ratio_done)
				 << "                          \r" << flush;
		}

		// This is where we actually run a benchmark!
		benchmarks[benchmark_index].run();
		benchmark_index++;
	}
}

void
run_benchmarks(vector<benchmark_t>& benchmarks)
{
	size_t first_benchmark_to_run;
	vector<benchmark_t> deserialized_benchmarks;
	bool use_deserialized_benchmarks = false;
	if (deserialize_benchmarks(session_filename, deserialized_benchmarks, first_benchmark_to_run)) {
		cerr << "Found serialized session with " << 100.0f * first_benchmark_to_run / deserialized_benchmarks.size()
			 << " % already done" << endl;
		if (deserialized_benchmarks.size() == benchmarks.size() && first_benchmark_to_run > 0 &&
			first_benchmark_to_run < benchmarks.size()) {
			use_deserialized_benchmarks = true;
		}
	}

	if (use_deserialized_benchmarks) {
		benchmarks = deserialized_benchmarks;
	} else {
		// not using deserialized benchmarks, starting from scratch
		first_benchmark_to_run = 0;

		// Randomly shuffling benchmarks allows us to get accurate enough progress info,
		// as now the cheap/expensive benchmarks are randomly mixed so they average out.
		// It also means that if data is corrupted for some time span, the odds are that
		// not all repetitions of a given benchmark will be corrupted.
		random_shuffle(benchmarks.begin(), benchmarks.end());
	}

	for (int i = 0; i < 4; i++) {
		max_clock_speed = max(max_clock_speed, measure_clock_speed());
	}

	double time_start = 0.0;
	while (first_benchmark_to_run < benchmarks.size()) {
		if (first_benchmark_to_run == 0) {
			time_start = timer.getRealTime();
		}
		try_run_some_benchmarks(benchmarks, time_start, first_benchmark_to_run);
	}

	// Sort timings by increasing benchmark parameters, and decreasing gflops.
	// The latter is very important. It means that we can ignore all but the first
	// benchmark with given parameters.
	sort(benchmarks.begin(), benchmarks.end());

	// Collect best (i.e. now first) results for each parameter values.
	vector<benchmark_t> best_benchmarks;
	for (auto it = benchmarks.begin(); it != benchmarks.end(); ++it) {
		if (best_benchmarks.empty() || best_benchmarks.back().compact_product_size != it->compact_product_size ||
			best_benchmarks.back().compact_block_size != it->compact_block_size) {
			best_benchmarks.push_back(*it);
		}
	}

	// keep and return only the best benchmarks
	benchmarks = best_benchmarks;
}

struct measure_all_pot_sizes_action_t : action_t
{
	virtual const char* invokation_name() const { return "all-pot-sizes"; }
	virtual void run() const
	{
		vector<benchmark_t> benchmarks;
		for (int repetition = 0; repetition < measurement_repetitions; repetition++) {
			for (size_t ksize = minsize; ksize <= maxsize; ksize *= 2) {
				for (size_t msize = minsize; msize <= maxsize; msize *= 2) {
					for (size_t nsize = minsize; nsize <= maxsize; nsize *= 2) {
						for (size_t kblock = minsize; kblock <= ksize; kblock *= 2) {
							for (size_t mblock = minsize; mblock <= msize; mblock *= 2) {
								for (size_t nblock = minsize; nblock <= nsize; nblock *= 2) {
									benchmarks.emplace_back(ksize, msize, nsize, kblock, mblock, nblock);
								}
							}
						}
					}
				}
			}
		}

		run_benchmarks(benchmarks);

		cout << "BEGIN MEASUREMENTS ALL POT SIZES" << endl;
		for (auto it = benchmarks.begin(); it != benchmarks.end(); ++it) {
			cout << *it << endl;
		}
	}
};

struct measure_default_sizes_action_t : action_t
{
	virtual const char* invokation_name() const { return "default-sizes"; }
	virtual void run() const
	{
		vector<benchmark_t> benchmarks;
		for (int repetition = 0; repetition < measurement_repetitions; repetition++) {
			for (size_t ksize = minsize; ksize <= maxsize; ksize *= 2) {
				for (size_t msize = minsize; msize <= maxsize; msize *= 2) {
					for (size_t nsize = minsize; nsize <= maxsize; nsize *= 2) {
						benchmarks.emplace_back(ksize, msize, nsize);
					}
				}
			}
		}

		run_benchmarks(benchmarks);

		cout << "BEGIN MEASUREMENTS DEFAULT SIZES" << endl;
		for (auto it = benchmarks.begin(); it != benchmarks.end(); ++it) {
			cout << *it << endl;
		}
	}
};

int
main(int argc, char* argv[])
{
	double time_start = timer.getRealTime();
	cout.precision(4);
	cerr.precision(4);

	vector<unique_ptr<action_t>> available_actions;
	available_actions.emplace_back(new measure_all_pot_sizes_action_t);
	available_actions.emplace_back(new measure_default_sizes_action_t);

	auto action = available_actions.end();

	if (argc <= 1) {
		show_usage_and_exit(argc, argv, available_actions);
	}
	for (auto it = available_actions.begin(); it != available_actions.end(); ++it) {
		if (!strcmp(argv[1], (*it)->invokation_name())) {
			action = it;
			break;
		}
	}

	if (action == available_actions.end()) {
		show_usage_and_exit(argc, argv, available_actions);
	}

	for (int i = 2; i < argc; i++) {
		if (argv[i] == strstr(argv[i], "--min-working-set-size=")) {
			const char* equals_sign = strchr(argv[i], '=');
			min_working_set_size = strtoul(equals_sign + 1, nullptr, 10);
		} else {
			cerr << "unrecognized option: " << argv[i] << endl << endl;
			show_usage_and_exit(argc, argv, available_actions);
		}
	}

	print_cpuinfo();

	cout << "benchmark parameters:" << endl;
	cout << "pointer size: " << 8 * sizeof(void*) << " bits" << endl;
	cout << "scalar type: " << type_name<Scalar>() << endl;
	cout << "packet size: " << internal::packet_traits<MatrixType::Scalar>::size << endl;
	cout << "minsize = " << minsize << endl;
	cout << "maxsize = " << maxsize << endl;
	cout << "measurement_repetitions = " << measurement_repetitions << endl;
	cout << "min_accurate_time = " << min_accurate_time << endl;
	cout << "min_working_set_size = " << min_working_set_size;
	if (min_working_set_size == 0) {
		cout << " (try to outsize caches)";
	}
	cout << endl << endl;

	(*action)->run();

	double time_end = timer.getRealTime();
	cerr << "Finished in " << human_duration_t(time_end - time_start) << endl;
}
